mc9s08sg4 Freescale Semiconductor, Inc, mc9s08sg4 Datasheet - Page 56

• Manufacturer Part Number: mc9s08sg4
• Description: 8-bit Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

1
Chapter 4 Memory
4.7.3
4.7.4
During reset, the contents of the nonvolatile location NVPROT is copied from FLASH into FPROT. This
register can be read at any time, but user program writes have no meaning or effect.
56
Background commands can be used to change the contents of these bits in FPROT.
KEYACC
Reset
Reset
Field
5
W
W
R
R
FLASH Configuration Register (FCNFG)
FLASH Protection Register (FPROT and NVPROT)
Enable Writing of Access Key — This bit enables writing of the backdoor comparison key. For more detailed
information about the backdoor key mechanism, refer to
0 Writes to 0xFFB0–0xFFB7 are interpreted as the start of a FLASH programming or erase command.
1 Writes to NVBACKKEY (0xFFB0–0xFFB7) are interpreted as comparison key writes.
0
0
7
7
= Unimplemented or Reserved
0
0
6
6
Figure 4-7. FLASH Configuration Register (FCNFG)
1
This register is loaded from nonvolatile location NVPROT during reset.
Figure 4-8. FLASH Protection Register (FPROT)
Table 4-10. FCNFG Register Field Descriptions
SEC01:SEC00 changes to 1:0 after successful backdoor
key entry or a successful blank check of FLASH.
MC9S08SG8 MCU Series Data Sheet, Rev. 3
SEC01:SEC00
KEYACC
0
5
5
0:0
0:1
1:0
1:1
Table 4-9. Security States
FPS
0
0
4
4
(1)
Description
Section 4.6,
Description
unsecured
secure
secure
secure
3
0
0
3
1
“Security.”
0
0
2
2
Freescale Semiconductor
0
0
1
1
FPDIS
0
0
0
0
(1)